ModernUO

Ultima Online Server Emulator for the modern era!

Requirements

Supported Operating Systems

Required Frameworks

All Operating Systems

Windows

Hardware

Use	vCPU	RAM	Storage
Development / test	2 dedicated	2 GB	SSD
Small live shard (< 50 concurrent)	4 dedicated	4 GB	NVMe
Medium (50–200)	4–8	8 GB	NVMe
Large (200+)	8+, high clock	16 GB+	NVMe

Game logic is single-threaded, so single-core clock speed matters more than core count, and dedicated vCPU matters more than either — burstable or shared plans throttle once credits run out, which is the most common cause of unexplained lag spikes. Save size drives RAM more than player count does.

See dev-docs/server-requirements.md for the reasoning and tuning options.

Development

Supported IDEs

Getting Started

• Install prerequisite requirements
• Clone this repository (or download the latest):
  • git clone https://github.com/modernuo/ModernUO.git
• Open ModernUO.sln to start developing

Building/Publishing

Interactive Mode (Recommended for new users)

Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:

• Check prerequisites (.NET SDK, native libraries)
• Walk you through configuration and platform selection
• Build and publish the server to the Distribution directory
• Show deployment instructions for cross-compiled builds

Command Line

./publish.cmd [release|debug] [os] [arch]

• os - Supported operating systems
  • win - Windows
  • osx - macOS
  • linux - Linux
• arch
  • x64 - Intel/AMD 64-bit
  • arm64 - ARM 64-bit

Linux Prerequisites

Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc

dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate libargon2 tzdata

Ubuntu, Debian, etc

apt-get update -y
# The ICU runtime package carries the ABI version in its name (libicu74, libicu76, …) and has no
# stable alias, so match it by pattern rather than pinning a release-specific name.
apt-get install -y '^libicu[0-9]+$' libdeflate0 libargon2-1 tzdata

Only the runtime libraries are needed — the -dev/-devel packages are not. Run ./build-tool --check-prereqs to check the current machine and print the exact packages your release needs.

zstd is not listed because ZstdNet bundles libzstd for every platform, and liburing is not listed because IORingGroup issues io_uring syscalls directly.

If the shard's configured time zone is a legacy alias such as US/Eastern, Debian 12 and Ubuntu 24.04 also need tzdata-legacy. See Platform Prerequisites for what each dependency is for and what breaks without it.

OSX Requirements

brew install icu4c libdeflate argon2

Running the Server

• Follow the publish instructions
• The Distribution directory is portable — copy it to your production server for deployment
• Run ModernUO.exe or dotnet ModernUO.dll from the Distribution directory
• On first run, the server will prompt you to configure game data file locations

Troubleshooting / FAQ

• See FAQ

Want to sponsor?

Thank you for supporting us! You can find out how by visiting the sponsors page.

Collaborators

Thanks

• RunUO Team & Community
• Voxpire, the ServUO Team & Community
• Karasho, Jaedan and the ClassicUO Community

Development Tools & Plugins provided with ♥ by

Code Signing Policy

Free code signing provided by SignPath.io, certificate by SignPath Foundation.

This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it

Teams & Roles

Approvers & Committers: Development Team